A 21-year-old St. Paul man has been convicted of first-degree murder for gunning down another man on a Merriam Park street about a year ago.

Aaron J. Morrow claimed self-defense when he shot Joe Anthony Rivera, 21, at least six times with an AK-47 assault rifle.

The shooting occurred early on Sept. 26, 2010, after one of Morrow's friends accused one of Rivera's friends of taking his cell phone during a party, and after Morrow went back to his mother's house in the West End neighborhood and retrieved the weapon.

Morrow alleged in a police interview that Rivera, whom he referred to as "Fat Joe," was part of a group that assaulted one of Morrow's friends a few years earlier. He deemed Rivera to be not only "trouble," he told police, but also "the worst scum of the earth."

The shooting, as such, was not self-defense, prosecutor Daniel Vlieger told a Ramsey County District Court jury during closing arguments Monday.

"This was vigilante justice," he said.

The jury deliberated about four hours before returning its verdict, which also convicted Morrow of the attempted murder of two of Rivera's friends: David Chavez of St. Paul, who was shot in the leg, and Gilberto Caldero of North St. Paul, who escaped injury. The trial took six days and included testimony from Morrow.

The shooting took place just after 3:30 a.m., about a half-block from a party in the 500 block of Prior Avenue.

Morrow, who had two jobs and no prior arrests at the time of the incident, fired 15 shots -- each of them requiring a separate pull of the trigger -- initially from behind an open car door and then while walking with the AK-47 at hip level.

He testified that he was at his mother's house playing a video game when his friend Randy White called from the party asking for a ride. White was drunk, scared and angry, Morrow said.

After arriving, Morrow witnessed a confrontation between White and Chavez regarding the cell phone, and when he sensed others were urging Chavez to fight, Morrow said, "Let's go."

While acknowledging the decision to then get a gun was a "bad move," defense attorney Gary Wolf said Morrow and White returned to the party only to get White's keys and sweater, which White left behind. White picked up the items outside the building. Then, Rivera, Caldero and Chavez stepped outside, and when White ran to Morrow's car, they followed.

In Wolf's view, the three walked as if from the "Gunfight at the OK Corral." To Caldero, he said, it was a case of "fight or flight." Morrow had no choice but to start shooting to protect himself and his "scared little buddy," Wolf said.

Vlieger argued that the shooting was premeditated. Morrow retrieved the gun when he knew the three were there, and he started heading back to the party before White even knew that his keys and sweater had been left behind: "He was a man on a mission at that point," Vlieger said.

Morrow parked a half-block from where the party was being held so that he could survey the scene, and when the three men followed White, "he called them closer" before he opened fire, Vlieger said.

"This was an intentional act," he said. "He pulled the trigger and he pulled the trigger."

Vlieger added that there was never any evidence presented that the years-old assault that Morrow referred to had occurred. Throughout the trial, Rivera's supporters took up more than half of the courtroom, and several could be heard sobbing when the verdicts were read.

District Judge John Guthmann set sentencing for 2:30 p.m. Tuesday. A first-degree murder conviction carries a mandatory sentence of life without parole.